SUB lcs (a$,b$)
    IF LEN(a$) = 0 OR LEN(b$) = 0 THEN
       PRINT ""
       EXIT SUB
    END IF
    DO WHILE LEN(b$)<>0
       FOR j = LEN(b$) TO 1 STEP -1
           IF POS(a$,(b$)[1:j])<>0 THEN
              PRINT (b$)[1:j]
              EXIT SUB
           END IF
       NEXT j
       LET b$ = (b$)[2:maxnum]
    LOOP
END SUB

CALL lcs ("thisisatest", "testing123testing")
END